Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0008272 (chlorosis)
 2,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In early 2008, tomato plants (Solanum lycopersicum) grown in a large greenhouse facility located near Mexico City exhibited general stunting, leaf chlorosis at the top of the diseased plant that later turned bronze or purple, and reduced-sized fruits. Initially, diseased plants were confined to a 5-ha greenhouse, but the disease quickly spread to two additional 5-ha greenhouses in the summer of 2008. By the end of 2008, approximately 5% of tomato plants in 35-ha of greenhouse were infected. Sixteen diseased samples were collected, twelve in 2008 and four in 2009. Bioassays through mechanical inoculation with leaf extracts of diseased samples demonstrated the transmissibility of the causal agent to plants of tomato cvs. Horizon or Rutgers, which expressed symptoms that were similar to those on the source plants. Serological or PCR assays were negative for several commonly occurring greenhouse tomato viruses. However, an expected size product (~196 bp) was consistently detected by reverse transcription (RT)-PCR using pospiviroid-specific primers Pospil-RE and Pospil-FW (4) in all symptomatic samples or from the mechanically inoculated tomato plants. Preliminary analysis with sequences obtained from direct sequencing of amplicons revealed one dominant sequence with 94% identity to Mexican papita viroid (MPVd) (GenBank Accessions Nos. L78454 and L78456-L78463). However, further analysis of the cloned cDNAs indicated a mixed infection of two pospiviroids in two samples. Of 10 cDNA clones analyzed, 9 were MPVd-like sequences and one was sequence of Tomato chlorotic dwarf viroid (TCDVd). Further analysis using full genomic sequences obtained by RT-PCR with previously designed primers (2) or a new set of primers (MTTVd-F: 5' GGG GAA ACC TGG AGC GAA CTG G, and MTTVd-R: 5' GGG GAT CCC TGA AGC GCT CCT) revealed genetic diversity in this population. Eight of thirteen cloned cDNAs represented by the 359-nt sequence of isolate Mex8 (GenBank Accession No. GQ131572) had 93 to 94% nucleotide sequence identity to other MPVd isolates (L78454 and L78456-L78463). Five other cDNA clones represented by the 361-nt sequence of isolate HM2 (GenBank Accession No. GQ131573) were 99% identical to a TCDVd isolate recently identified in Arizona (GenBank Accession No. FJ822878) and 96 to 97% identical to TCDVd isolates from other areas (GenBank Accession Nos. AF162131 and AB329668). These results are the first evidence of a mixed infection of two viroids infecting tomatoes in Mexico. MPVd was first identified in Mexico on papita (S. cardiophyllum) in 1996 (1). The origin of TCDVd in this greenhouse was not determined, but TCDVd potentially can be seed transmitted in tomato (3). The close relationship between the Mexican and the U.S. isolates suggests that TCDVd in these two countries may share a common origin, likely from seed. To our knowledge, this is the first report of a natural infection of MPVd and TCDVd on tomatoes in Mexico. References: (1) J. P. Martinez-Soriano et al. Proc. Natl. Acad. Sci. U.S.A. 93:9397, 1996. (2) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997. (3) R. P. Singh and A. D. Dilworth. Eur. J. Plant Pathol. 123:111, 2009. (4) J. Th. J. Verhoeven et al. Eur. J. Plant Pathol. 110:823, 2004.
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PMID:First Report of a Natural Infection by Mexican Papita Viroid and Tomato Chlorotic Dwarf Viroid on Greenhouse Tomatoes in Mexico. 3075 7

Dahlia (Dahlia variabilis Hort.) is a significant ornamental plant in New Zealand. Symptoms such as mosaic, ring spots, mottling, and veinal chlorosis, suggestive of a viral infection, are often seen in various dahlia collections. To better understand the incidence of viruses in dahlia in New Zealand, several popularly grown cultivars were evaluated for viruses that are known to infect dahlia. Viruses that were tested included Cucumber mosaic virus (CMV), Dahlia mosaic virus (DMV), Impatiens necrotic spot virus (INSV), Tobacco streak virus (TSV), and Tomato spotted wilt virus (TSWV). At least one symptomatic plant was tested from each of the following cultivars: Akito Dawn, Cincinnati Dancer, Hamari Accord, Hamari Rose, LeBatts Prime, LeVonne Splinter, Riverlea Tropicana, Spartacus, Tartan, Tui Connie, and Wandas Antartica. Except for DMV, initial testing was done by ELISA with commercially available kits for the above viruses. In the case of dahlia mosaic, samples were tested for DMV that was described previously (4) and two additional and distinct caulimoviruses (DMV-D10 and DMV-Holland) that were found to be associated with dahlia (1,2). Primer pairs, ORF6st: ATG GAA GAA ATT AAG GCG T and ORF6end: TTG TCT TCA TCC ATA AAG CAG; DenF1: CAG CAA GAA ACA GGA ATT GA and DenR: TTA CAG TCG AAG CTG CTA AA; and Kapht-F: ATG AGT AAT GCT TCA GCA A and Kapht-R: TGA CCA TGG CTT CTA ACT GT were used for the specific detection of DMV-D10, DMV-Holland, and DMV, respectively (1). None of the samples tested were ELISA positive for CMV, INSV, or TSWV. To verify the TSV infection, TSV-specific primers (5'-GTC CAG ACC ATC CAT CCA AC-3' and 5'-TTG ATT CAC CAG GAA ATC TT-3'), designed based on sequences available in GenBank, were used in reverse transcription (RT)-PCR. For DMV, the diagnostic tests used were electron microscopy and PCR followed by amplicon cloning and sequencing. Electron microscopic observation of leaf-dip preparations showed near isometric virions, approximately 50 to 60 nm in all samples tested. PCR showed that all samples tested were positive for DMV-Holland and DMV-D10. While DMV-Holland is a typical caulimovirus, DMV-D10 was found to exist as an endogenous plant pararetroviral sequence in dahlia (3). One sample each from two cultivars, Spartacus and Tui Connie, were positive for TSV by ELISA, RT-PCR, followed by the sequence analysis of the cloned amplicon. The impact of TSV-infected dahlias as a potential source of inoculum remains to be seen. Our results suggested the prevalence of dahlia mosaic-associated caulimoviruses in several dahlia cultivars and the presence of TSV in New Zealand dahlias. Dahlia mosaic continues to be prevalent in several parts of the world (1), and with the current findings in New Zealand, testing for these viruses should be conducted to ensure virus-free status of the propagating material. References: (1) V. Pahalawatta et al. Plant Dis. 91:1194, 2007. (2) V. Pahalawatta et al. Arch. Virol.153:733, 2008. (3) V. Pahalawatta et al. Virology 376:253, 2008. (4) R. D. Richins and R. J. Shepherd. Virology 124:208, 1983.
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PMID:Dahlia mosaic virus and Tobacco streak virus in Dahlia (Dahlia variabilis) in New Zealand. 3076 5